Fractionation of hydrocarbons



June 23, 1942. A. R. NEVITT 2,287,355

FRACTIONATION OF HYDROCARBONS Filed June 5. 1959 STEAM Patented June 23, 1942 FRACTIONATION OF HYDROCARBON S Albert Ramsey Nevitt, New Brunswick, N. J., as-

signor to Bradford Penn Refining Corporation, Clarendon, Pa., a corporation of Pennsylvania Application June 5, 1939, Serial No. 277,418 7 claims. (ci. 19e-13) The invention here disclosed relates to the fractionation of hydrocarbons.

Special objects of the invention are to accomplish the chemical separation of complex petroleum hydrocarbons into pure hydrocarbon fractions of stable boiling range and to provide a medium which upon mixturev with a complex petroleum hydrocarbon having a long boiling range differential will absorb a selected pure hydrocarbon fraction, according to its boiling range and specific gravity.

Other important objects are to provide a selective solvent which will separate complex hydrocarbon mixtures without altering the original chemical characteristics of either the solvent or of the extracted hydrocarbon fraction.

Other, more specific objects and the novel features by which the purposes of the invention are attained, will appear or are set forth in the following specification.

The drawing accompanying and forming part of the specification is illustrative of details of the invention, but as will appear, various changes and modifications may be made, all within the true spirit and broad scope of the invention.

Fig. 1 is a broken part sectional view of one of the cooker units.

Fig. 2 is a diagrammatic view illustrating a battery of such units.

Figs. 3 and 4 are diagrammatic views illustrating steps in effecting the fractionation.

It is known that petroleum hydrocarbons are of complex character, both in the natural and in the refined state.

By suitable heat exchange, ashingoperations and distillation processes, crude petroleum is usually separated into commercial specification products, such as normal hexane, benzine, gasoline, naphtha, kerosene, light distillate, gas oil, fuel oils, lubricants, waxes and petrolatum.

Each of these cornmerclal products is a com,- plex compound having a wide distillation boiling range. Thus normal hexane, the lightest of those mentioned which is liquid at normal temperatures, has a range of 70 F. to 190 F. It is known that for each degree of temperature, there is a distinct pure hydrocarbon having a constant boiling point and Aspecific gravity. Hence this one product, normal hexane, with an 4initial boiling point of 70 F. and an end point of 190 F. is composed of some 120 different pure hydrocarbons. Similarly, the benzine cut, boiling in the range of 180 F. to 260 F. is composed of some 80 pure hydrocarbons, gasoline, in a substitutes for ether used in the extraction of range of F.-400 F., is composed of some 305 55 delicate essential oils, Where a low steady tem-l perature is required to prevent decomposition of the oils and wherein recovery of the solvent is then relatively simple.

The heavier pure hydrocarbons are of special value in the de-gumming of rayon and resinous ligneous fibers.

The extraction of the pure hydrocarbons by known methods is costly, involving intricate fractionating problems, requiring much apparatus, so that cost of production is largely prohibitive. Under known methods, the crude is rst distilledinto complex fractions of wide boiling range and then these are repeatedly distilled into fractions of narrower boiling limit, until desired specifications are finally obtained. Such methods necessarily introduceobjectionable features. Impurities are created, such as peroxides, which form gum and the like. Also there is a concentration of the mercaptans and other sulphurous compounds, resulting from the repeated heating and reheating. The nished distillates then require treatment, such as with sulphuric acid and sodium hydroxide for'removal 4of the impurities.

Under the present invention, fractionation of the pure hydrocarbons is accomplished by admixture of a chemical compound in certain steps and without use of heat or distillation.

The solvent compound, according to o'ne practical example, is made as follows:

A kerosene containing parain in excess of 49% is placed in a closed cooking vessel, such as indicated at 5, Figs. 1 and 2. This is heated to a temperature of approximately F. and at such temperature tin naphthenate is added whilst agitating, at the rate of approximately 1 cc. of tin naphthenate per gallon of hydrocarbon.

Air is then turned into the mixture through the line 6', connected with the submerged downf wardly directed spray coil or lpipe 1, until an abundance of white fumes is `given off. This is continued for a period hours or until the mass of about 1160 Klett units.

The mass is then allowed to'settle and cool to approximately '70 F. This settling effects a separation of a thick viscous liquid constituting approximately 20% of the whole and forming an oxidation product of the hydrocarbon.

The separated and settled material is withdrawn from the bottom through draw-oil line 8.

A 5% hypochlorite solution is then added to the cooking vessel. This solution contains approximately 45 grams of available chlorine per liter.

Air is again blown into the mixture through the line 6, for a period of approximately 8 hours.

Water is drawn off and after addition of fresh hypochlorite, blowing is continued untilthe solution refuses to take up any more chlorine.

The oxidation products first separated and removed are next added to the contents of the vessel and blowing continued for a. period of about 6 to 8 hours.

The water which was removed during the chlorination is treated with sodium chloride, about grams per liter and returned to the batch being treated.

The whole mix is then heated with steam, admitted through line 9, to the downwardly directed spray pipe or head l0, submerged in the bottom of the chamber, to a temperature of about 180 F.

Blowing with air is again continued for approximately 8 hours, after which the mass is permitted to settle.

In this last operation, a thick white mass settles, amounting to approximately 15% of the charge and containing much calcium.

The settled liquid is then filtered through Fullers earth.

The B. gravity which originally was about 4041 will now be aboutA 30-34 and may be concentrated to as low as 28 B.

The finished compound is soluble in both oil and water and has some of the characteristics of an alcohol.

This substance has been named methylethyltetraoxychloride.

Preparation of the solvent may be facilitated and expedited by use of a battery of the cookers, such as illustrated in Fig. 2, these being independently controllable to best carry out the desired operations.

A specific example of use of the solvent for fractionation or extraction purposes is as follows:

500 cc. of i gasoline with an I. B. P. of 95 F. and an end point of 400 F., and designated Il, is placed in a ask or container l2, and 500 cc. of the methylethyltetraoxychloride designated I3, is added and the mixture agitated and then permitted to settle. The solvent mixing with the hydrocarbon, which is 65 B., so changes its gravity that approximately 50% is absorbed by the chemical solution, throwing the lighter constituents to the top, as indicated in the second diagram of Fig. 3. The amount of absorption taking place depends upon the concentration of the chemical solution in the initial step. Apparently the chemical compound has a greater ainity for the aromatic and naphthenic constituents in gasoline. However, after the first step of absorption, the remaining paraftlns are easily taken up by the solution.

The separated portion whichlfloats on the top is removed to a second flask I4, and a further of usually about 18 has attained a color amount of the solution added, such as in the present example 250 ccna substantially equal amount. A changing of gravities again takes place with the result indicated in the third diagram of Fig. 3. The lighter constituents are again removed and the process repeated until all of the hydrocarbons have been absorbed in successive steps, each treat being kept separate.

The mixture of dissolved hydrocarbon and chemical in the first flask I2, is then treated with water, approximately a drop at a time. As each drop of water enters the solution, the chemical, having a greater affinity for the water, changes its gravity, giving up a hydrocarbon of a certain gravity. With each subsequent addition of water, a diierent hydrocarbon is liberated from `the solution and each in turn, is separately removed as indicated in Fig. 4 and water removed.

These removed hydrocarbons are of great purity.

Each flask is treated in like manner. The remaining chemical solution is re-distilled to remove the water which has been added and is then again ready for re-use.

The invention thus `enables the chemical separation of complex petroleum hydrocarbons into pure hydrocarbon fractions of stable boiling point and provides a medium which will accomplish such selection without alteration of its original character or of the extracted fraction.

The necessary heat may be furnished entirely by the steam spray coil and suihcient agitation may be furnished by the air admitted through the air spray coil.

What is claimed is:

1. The process of converting a hydrocarbon material containing in excess of 49% parains and having an initial boiling point ranging between 270 F. and 300 F. and an end boiling point between 470 F. and 520 F., into ka selective solvent capable of reacting with other hydrocarbons of the same grouping and boiling within narrow limits, thus to separate them into selective pure hydrocarbons, said process comprising heating a paraffin hydrocarbon and contacting the same with an aqueous solution of metallic salts capable of promoting oxidation of the parans, passing air therethrough while the hydrocarbon is in contact with said solution, removing the oxidized portion of the mixture, chlorinating the remaining portion of said mixture under conditions to form a super-saturated solution, removing part of said solution containing Water, adding sodium chloride to said removed water containing part of said solution, returning the thus treated water containing part of the solution and the oxidized portion of the mixture rst removed to the chlorinated portion of the mixture, reheating the thus combined mass, treating with air suiciently to aid combination of the oxidized portion with the chlorinated portion, settling out the undesired portion and then filtering and decolorizing the remaining desired solvent portion with adsorbent medium to form a solvent soluble in water and petroleum hydrocarbons.

2. Those steps in the preparation of a selective petroleum solvent capable of reacting with other hydrocarbons, comprising heating a paraiinic hydrocarbon boiling between 270 F. and 520 F. to a temperature of about 180 F. for a period in the neighborhood of eighteen hours in the presence of tin naphthenate and oxidizing by passing a stream of air therethrough.

3. Those steps in the preparationof a selective petroleum solvent capable of reacting with other hydrocarbons, comprising heating a paraiiinic hydrocarbon boiling between 270 F. and

520 F. to a temperature of about 180 F. for a period in the neighborhood of eighteen hours in the presence -of tin naphthenate, oxidizing by passing a stream of air therethrough, separating the products of oxidation, chlorinating the remaining portion in thepresence of air, returning the oxidation products to the mixture to effect further chemical reaction and treating the mass with air for a further period of about eight hours.

4. Those steps in the preparation of a selective petroleum solvent, capable of reacting with other hydrocarbons, comprising heating a parainic hydrocarbon boiling between 270 F. and 520 F. to a temperature of about 180 F. for a period in the neighborhood of eighteen hours in the presence of tin naphthenate, oxidizing by passing a stream of air therethrough, separating the products of oxidation, chlorinating the remaining portion in the presence of air and to an extent to create a watery condition, returning the oxidation products to the mixture to eiect further chemical reaction, treating the mass with air for a further period of about eight hours, intermittently removing the watery portion during the chlorination period, treating the watery portion with sodium chloride, returning the thus treated portion to the chlorinated portion to effect a separation of calcium soaps and filtering and decolorizing the solvent portion.

5. `Those steps in the preparation of a selective' petroleum solvent, capable of reacting with other hydrocarbons, comprising heating a paranic hydrocarbon boiling between 270 F. and 520 F. to a temperature of about 180 F. for a period in the neighborhood of eighteen hours in the presence of tin naphthenate, oxidizing by passing a stream of air therethrough, separating the products of oxidation, chlorinating the remaining portion in the presence of air and to an extent to create a watery condition, returning the oxidation products to the mixture to effect further chemical reaction, treating the mass with air for a further period of about eight hours, intermittently removing the watery portion during the chlorination period, treating the watery portion with sodium chloride and then returning the thus treated portion to the chlorinated portion.

6. The process of converting a para'inic base hydrocarbon oil having an initial boiling point between 270 F. and 300 F. into a selective solvent which will enter into combination with other hydrocarbons of the same grouping but of diiierf ent molecular structure and boiling within narrow limits to effect separation of pure selective hydrocarbons, said process comprising heating a parainic base hydrocarbon oil in the presence of a naphthenic tin solution capable of promoting oxidation of the parains, passing air through the mixture to form peroxides with the parailins present in turbulent contact with the metallic solution, removing the portions of the mixture so oxidized, chlorinating the remaining portion of the mixture with a calcium'hypochlorite solution until a residual chlorine solution is obtained in combination with a hydrocarbon mixture, removing said residual chlorine solution, adding sodium chloride to said removed chlorine solution to precipitate the calcium soaps, returning the lastl treated solution together with the oxidation products first removed to the chlorinated portion of the mixure, reheating the combined mass, treating with air to accelerate combination of contained peroxides with the chlorinated hydrocarbons, settling out an undesired portion and then ltering and decolorizing the remaining portion with an adsorbent medium until a nal solvent is obtained partly soluble in petroleum and completely soluble in water.

7. Those steps in the preparation of a selective petroleum solvent capable of combining with other liquid hydrocarbons of the same grouping, which comprises-heating a paraiiin base hydrocarbon between an initial boiling point of 270 F. and an end boiling point of 520 F. to a temperature of about 175 F. to 185 F. for a period of about 17 to 19 hours in the presence of a tin naphthenate solution, effecting accelerated oxidation by passing a rapid turbulent stream of air therethrough, cooling the mixture, separating out products of oxidation (mainly peroxides), chlorinating the remaining portion with a calcium hypochlorite solution while passing a stream of air therethrough and at a temperature between F. and 200 F. for an approximate period of between 40 and 48 hours, returning the oxidized products to said chlorinated portion to effect further chemical reaction and blowing with a violent stream of air for a further period of approximately 8 hours.

ALBERT RAMSEY NEVI'IT. 

